1. Field of the Invention
The present invention relates generally to a locking arrangement for preventing unauthorized operation of a flow control valve, and more particularly pertains to a magnetically locked fluid valve designed for a fire hydrant to prevent unauthorized usage thereof.
2. Discussion of the Prior Art
Fire hydrants in prevelant usage today comprise a stand pipe which extends upwardly from an elbow which is connected to the main water supply pipe line. A control valve is located at the juncture between the bottom of the stand pipe and the elbow for controlling the flow of water to the fire hydrant. At its upper end, the stand pipe is provided with an above ground portion of barrel which includes at least one steamer nozzle or outlet nozzle extending laterally therefrom. A control valve operating rod also extends upwardly from the control valve through the barrel portion to the top thereof whereat it is accessible to authorized personnel for opening the control valve when desired, such as in the case of a fire when a fire hose is connected to the fire hydrant.
Unfortunately, a fire hydrant of this type is completely unprotected against unauthorized usage and may be operated at will by nonauthorized persons. The resultant water loss, and drop in water pressure, is a matter of serious concern to many cities.
Unauthorized persons are able to open the fire hydrant by gaining access to an operating nut at the upper end of the operating rod and opening the control valve.
Prior art attempts to prevent the unauthorized operation of fire hydrants have generally been directed to preventing access to the operating mechanism at the upper end of the barrel. However, this has not proved to be a satisfactory solution, and the problem in most cities is still a very serious one which has not been solved.
Thompson U.S. Pat. No. 3,939,861 is of interest by disclosing a fire hydrant designed to prevent unauthorized use of an outlet nozzle which is located on the above ground barrel portion of the stand pipe. The hydrant includes a valve located within the barrel portion and provided with a valve member which is spring biased to a closed position extending across the upstream end of the outlet nozzle. A valve actuator is provided for moving the valve member from its closed position to its open position against the bias of the spring means. To this end, a collar is adapted to be mounted on the fire hydrant by authorized persons in a position surrounding the outlet nozzle. The collar carries a valve actuating member which is arranged to move into the outlet nozzle to contact the valve member to move it from a closed position to an open position as the collar is mounted on the fire hydrant. In summary this arrangement is rather complex, and would be an extremely expensive system to emplement when considering all of the replacement fire hydrants and hose collars required thereby.